Fraunhofer IIS just presented HD-AAC at the Consumer Electronics Show in Las Vegas. It's a hybrid format which can be played back as conventional AAC on legacy devices. HD-AAC capable devices also read the SLS layer and get a lossless reconstruction of the original signal.

MPEG-4 SLS is not really news, but Fraunhofer finally seems to be pushing this out to a broader public now. Decoders are supposed to be ready within 12 weeks for literally all current (mobile and stationary) hardware platforms.

Seems to be a great product, I hope Apple picks this up!

It's probably not necessarily better than other hybrid solutions. But it would be nice if it got enough momentum to be implemented into the top line of mobile players and their ecosystems. For example, if you would be able buy HD-AAC in the iTMS and then let it copy just the AAC-LC part to your iPod.